The high risk breast cancer clinic (HRBCC) is one of six sites comprising the Cooperative Family Registry for Breast Cancer Studies which is funded through a cooperative agreement from the NCI. The primary objective of this project is to collect pedigree information, epidemiologic data, and biological samples from individuals with a strong family history of breast and/or ovarian cancer. The ultimate objective is to identify population at high risk for breast cancer who could be enrolled in chemoprevention trials and other studies. The Utah HRBCC has currently enrolled 521 individuals from 178 families. DNA, plasma, and lymphoblast cell lines have been established for all. Most subjects have been genotyped for BRCA1 and BRCA2 mutations. In 33 pedigrees so far analyzed, 78 individuals have been found to have familial mutations of one of these two genes. Several new mutations (deletions and point mutations) have been identified. In 47 families no mutations could be identified and materials from these pedigrees will be useful in identifying new breast cancer genes.